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Date:      Mon, 10 Feb 2014 17:29:59 +0100
From:      =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
To:        Karl Pielorz <kpielorz_lst@tdx.co.uk>, <freebsd-xen@freebsd.org>
Subject:   Re: Xen PV Networking issue - disable PV NIC in XENHVM FreeBSD?
Message-ID:  <52F8FE87.1010705@citrix.com>
In-Reply-To: <D280F84BE886E8D6110B93D0@study64.tdx.co.uk>
References:  <D280F84BE886E8D6110B93D0@study64.tdx.co.uk>

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On 08/02/14 16:03, Karl Pielorz wrote:
> 
> Hi,
> 
> I've got an 'issue' (more with Xen than FreeBSD) - the upshot is, I need
> to disable the PV NIC (xn) from a VM running XENHVM kernel.
> 
> Is this possible? - In an ideal world I'd like to keep the storage
> drivers etc. - I just need to use the HVM 're' interface, not 'xn'
> interface...
> 
> For those who want to know what the issue is - we have a number of VM's
> on 1 Xen machine (e.g. 'Xen1') all using PV drivers (Windows and FreeBSD
> VM's). A FreeBSD VM is the 'default' gateway for the others - and it
> doesn't work :(
> 
> Packets are either going missing - or getting mangled. If you 'migrate'
> one of those hosts to another Xen machine in the pool (e.g. Xen2) it works.
> 
> If you migrate the default gateway VM over to the other Xen machine -
> all the other VM's on the original XenServer suddenly work (i.e. can see
> the outside world) - alternatively if you switch from PV drivers to HVM
> drivers on the affected guests - everything works, regardless of whether
> the VM's are on Xen1, Xen2 - or the same XenServer as the default
> gateway VM.
> 
> Only PV <-> PV shows the issue, and only when they're both hosted on the
> same XenServer.
> 
> Hence wondering about disabling the PV nic on the default gateway,
> instead of having to do it on all the other VM's...

That's quite weird... Do you see any messages in the Xen console (xl
dmesg)? Can you boot with a hypervisor compiled with debug=y and see if
there are any strange messages on the Xen console?

Also, does replacing the FreeBSD gateway VM with a Linux PV VM solve the
issue? (ie. just to check if Linux also shows this behaviour)

Roger.




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